Ryan Carney: “Missing Link” Dinosaur Had Black Feathers

Berlin specimen of Archaeopteryx - Paleontologists have long thought that Archaeopteryx fossils, including this one discovered in Germany, placed the dinosaur at the base of the bird evolutionary tree. Credit: Museum für Naturkunde Berlin

To determine the color of the winged dinosaur Archaeopteryx, scientists used a scanning electron microscope to analyze a fossilized feather from one of the raven-size creatures. The fossil was discovered in a limestone deposit in Germany in 1861.

The team was surprised to discover that the microscopic structure of the ancient wing feather was identical to that of modern bird plumage.

“It means that completely modern flight feathers had evolved as early as 150 million years ago, in the Jurassic period,” said study leader Ryan Carney, an evolutionary biologist at Brown University in Providence, Rhode Island.

Tracing Archaeopteryx’s Colors

With the aid of the specialized microscope, Carney and his team also picked out clusters of structures called melanosomes in the feather.

Melanosomes contain pigments called melanins and are responsible for a variety of functions in animals and birds, including giving hair and feathers their colors.

Melanosomes’ shapes—from spherical to rod-shaped—and their arrangement in cells are associated with particular feather colors.

To determine the original color of the Archaeopteryx feather, the team compared the dinosaur’s melanosomes with those in 115 modern feathers.

Based on the shapes and sizes of the modern melanosomes, the team concluded with 95 percent certainty that at least one of Archaeopteryx’s wing feathers was black.

Why Black Feathers Are Better

Hans-Dieter Sues, a paleontologist at the National Museum of Natural History in Washington, D.C., said the findings are “certainly suggestive.”

“Black is a common color for bird plumage, and its occurrence in Archaeopteryx would not be unusual,” said Sues, who was not involved in the study, published this week in the journal Nature Communications.

For birds, black feathers provide certain flight advantages. That’s because black feathers contain more pigment-packed melanosomes than do feathers of other colors, and melanosomes can bind with keratin proteins in feathers to make them thicker, stronger, and more durable.

Ryan Carney and colleagues determined that the 150-million-old Archaeopteryx feather was black, which would have provided structural advantages to the raven-sized dinosaur's wings during flicht. Photo: Mike Cohea/Brown University

“Studies have found that wing feathers are the most likely feathers to be pigmented black,” said Carney, who is also a National Geographic Society Waitt grantee. (The National Geographic Society owns National Geographic News.)

“And it’s why even white birds will often have black tips on their wings.”

Having black—and thus stronger—wing feathers could’ve helped Archaeopteryx as it flapped or coasted between trees.

Flight Debate Still Up in the Air

However, the new finding is unlikely to help settle the debate about whether Archaeopteryx was primarily a flier or a glider, study leader Carney said.

“Whether it was using its wings for flying or gliding, its feathers would still have been strengthened by having these melanosomes,” he added.